gnptab encodes the alpha/beta precursor of UDP-N-acetylglucosamine:lysosomal-enzyme N-acetylglucosamine-1-phosphotransferase, a Golgi enzyme that initiates mannose-6-phosphate tagging of lysosomal hydrolases. The core function is GlcNAc-1-phosphotransferase activity in N-glycan processing to lysosome; craniofacial, cartilage, bone, and heart phenotypes are downstream consequences of impaired lysosomal enzyme targeting.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003976 UDP-N-acetylglucosamine-lysosomal-enzyme N-acetylglucosaminephosphotransferase activity | IBA GO_REF:0000033 | ACCEPT | Summary: UDP-N-acetylglucosamine-lysosomal-enzyme N-acetylglucosaminephosphotransferase activity (GO:0003976) is the core molecular function of gnptab. Falcon deep research confirms this directly for the zebrafish protein: a structural study crystallized a zebrafish GNPTAB catalytic construct (UniProt Q5RGJ8) with bound UDP-GlcNAc and resolved the phosphotransfer mechanism, and the enzyme transfers phospho-GlcNAc from UDP-GlcNAc to the 6-hydroxyl of mannose on N-glycans of lysosomal hydrolases, requiring Mg2+ or Mn2+. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: file:DANRE/gnptab/gnptab-uniprot.txt Catalyzes the formation of mannose 6-phosphate recognition markers on lysosomal enzymes PMID:23733939 mediates the initial step in the formation of the mannose 6-phosphate recognition signal on lysosomal acid hydrolases file:DANRE/gnptab/gnptab-deep-research-falcon.md Zebrafish GNPTAB catalyzes the first step of M6P tag formation by transferring **phospho-GlcNAc** from **UDP-GlcNAc** to the **6-hydroxyl of mannose** on N-glycans (including high-mannose glycans of lysosomal hydrolases). |
| GO:0005794 Golgi apparatus | IBA GO_REF:0000033 | ACCEPT | Summary: Golgi apparatus (GO:0005794) is supported for gnptab. Falcon deep research confirms GNPTAB functions in the cis-Golgi with catalytic surfaces oriented toward the Golgi lumen, supported by structural topology and colocalization with the cis-Golgi marker GM130. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: file:DANRE/gnptab/gnptab-uniprot.txt Catalyzes the formation of mannose 6-phosphate recognition markers on lysosomal enzymes PMID:23733939 mediates the initial step in the formation of the mannose 6-phosphate recognition signal on lysosomal acid hydrolases file:DANRE/gnptab/gnptab-deep-research-falcon.md GNPTAB functions in the **cis-Golgi**, with its catalytic surfaces oriented toward the **Golgi lumen**, consistent with both structural topology and colocalization evidence (GM130 marker). |
| GO:0016256 N-glycan processing to lysosome | IBA GO_REF:0000033 | ACCEPT | Summary: N-glycan processing to lysosome (GO:0016256) is supported for gnptab. Falcon deep research describes GNPTAB as initiating the M6P sorting signal, the first step of the two-step M6P tagging pathway that routes lysosomal hydrolases; loss of GNPT activity abolishes M6P labeling and causes missorting/secretion of lysosomal enzymes. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: file:DANRE/gnptab/gnptab-uniprot.txt Catalyzes the formation of mannose 6-phosphate recognition markers on lysosomal enzymes PMID:23733939 mediates the initial step in the formation of the mannose 6-phosphate recognition signal on lysosomal acid hydrolases file:DANRE/gnptab/gnptab-deep-research-falcon.md GNPTAB supplies the initiating enzymatic step by transferring **GlcNAc-1-phosphate** from **UDP-GlcNAc** to **mannose residues** on high-mannose N-glycans, yielding a **GlcNAcβphosphateβmannose** intermediate that is subsequently processed ("uncovered") to expose M6P for receptor-mediated trafficking. |
| GO:0000139 Golgi membrane | IEA GO_REF:0000044 | ACCEPT | Summary: Golgi membrane (GO:0000139) is supported for gnptab. Falcon deep research confirms the GNPT complex is membrane-associated, with GNPTAB anchored via multiple transmembrane helices that place its luminal active sites in cavities oriented away from the membrane toward the Golgi lumen. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: file:DANRE/gnptab/gnptab-uniprot.txt Catalyzes the formation of mannose 6-phosphate recognition markers on lysosomal enzymes PMID:23733939 mediates the initial step in the formation of the mannose 6-phosphate recognition signal on lysosomal acid hydrolases file:DANRE/gnptab/gnptab-deep-research-falcon.md The GNPT complex is membrane-associated; structural work describes GNPTAB anchoring via multiple transmembrane helices, placing luminal active sites in surface cavities oriented away from the membrane. |
| GO:0003976 UDP-N-acetylglucosamine-lysosomal-enzyme N-acetylglucosaminephosphotransferase activity | IEA GO_REF:0000120 | ACCEPT | Summary: UDP-N-acetylglucosamine-lysosomal-enzyme N-acetylglucosaminephosphotransferase activity (GO:0003976) is supported for gnptab. Falcon deep research corroborates the EC 2.7.8.17 phosphotransferase identity with structural and biochemical evidence from a zebrafish Q5RGJ8 catalytic construct. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: file:DANRE/gnptab/gnptab-uniprot.txt Catalyzes the formation of mannose 6-phosphate recognition markers on lysosomal enzymes PMID:23733939 mediates the initial step in the formation of the mannose 6-phosphate recognition signal on lysosomal acid hydrolases file:DANRE/gnptab/gnptab-deep-research-falcon.md GlcNAc-1-phosphotransferase (GNPT) is a **phosphotransferase** (not a glycosyltransferase) that uses **UDP-GlcNAc** as phosphate-sugar donor; it requires **Mg2+ or Mn2+** for activity, consistent with metal coordination of phosphate groups in the active site. |
| GO:0005509 calcium ion binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: calcium ion binding (GO:0005509) is retained as supported context for gnptab but is not the primary/core function. This annotation derives from an EF-hand domain (IPR018247/IPR002048) within GNPTAB; falcon deep research notes GNPTAB contains an EF-hand Ca2+-binding domain among its accessory modules, but the catalytic phosphotransfer reaction is the core molecular function. Reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the central molecular role. Supporting Evidence: file:DANRE/gnptab/gnptab-uniprot.txt Catalyzes the formation of mannose 6-phosphate recognition markers on lysosomal enzymes PMID:23733939 mediates the initial step in the formation of the mannose 6-phosphate recognition signal on lysosomal acid hydrolases file:DANRE/gnptab/gnptab-deep-research-falcon.md GNPTAB contains a multipart **catalytic domain** plus accessory modules including **DMAP1-binding-like domain**, **Notch/EGF-like repeats**, **immunoglobulin-like domain**, **RRM-like/N-terminal modules**, and an **EF-hand Ca2+-binding domain**; these accessory regions contribute to selective hydrolase recognition. |
| GO:0015031 protein transport | IEA GO_REF:0000117 | KEEP AS NON CORE | Summary: protein transport (GO:0015031) is retained as supported context for gnptab but is not the primary/core function. It is a broad downstream consequence: by generating the M6P signal, GNPTAB enables M6P-receptor-mediated delivery of lysosomal hydrolases. The more specific term GO:0016256 (N-glycan processing to lysosome) better captures the core role. Reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the central molecular role. Supporting Evidence: file:DANRE/gnptab/gnptab-uniprot.txt Catalyzes the formation of mannose 6-phosphate recognition markers on lysosomal enzymes PMID:23733939 mediates the initial step in the formation of the mannose 6-phosphate recognition signal on lysosomal acid hydrolases file:DANRE/gnptab/gnptab-deep-research-falcon.md GNPTAB initiates **M6P-dependent lysosomal enzyme targeting**, enabling subsequent recognition by **cation-independent/cation-dependent M6P receptors** and delivery of hydrolases to lysosomes; loss of GNPT causes missorting/secretion of lysosomal enzymes and MLII/III pathology. |
| GO:0016772 transferase activity, transferring phosphorus-containing groups | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: transferase activity, transferring phosphorus-containing groups (GO:0016772) is retained as supported context for gnptab but is not the primary/core function. It is a broad parent of the specific phosphotransferase activity (GO:0003976); falcon deep research confirms GNPTAB is a phosphotransferase (not a glycosyltransferase) transferring phospho-GlcNAc from UDP-GlcNAc. Reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the central molecular role. Supporting Evidence: file:DANRE/gnptab/gnptab-uniprot.txt Catalyzes the formation of mannose 6-phosphate recognition markers on lysosomal enzymes PMID:23733939 mediates the initial step in the formation of the mannose 6-phosphate recognition signal on lysosomal acid hydrolases file:DANRE/gnptab/gnptab-deep-research-falcon.md GlcNAc-1-phosphotransferase (GNPT) is a **phosphotransferase** (not a glycosyltransferase) that uses **UDP-GlcNAc** as phosphate-sugar donor; it requires **Mg2+ or Mn2+** for activity, consistent with metal coordination of phosphate groups in the active site. |
| GO:0000139 Golgi membrane | ISS GO_REF:0000024 | ACCEPT | Summary: Golgi membrane (GO:0000139) is supported for gnptab. Falcon deep research confirms GNPTAB is membrane-anchored with luminal active sites oriented toward the Golgi lumen, supported by structural topology and colocalization with the cis-Golgi marker GM130. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: file:DANRE/gnptab/gnptab-uniprot.txt Catalyzes the formation of mannose 6-phosphate recognition markers on lysosomal enzymes PMID:23733939 mediates the initial step in the formation of the mannose 6-phosphate recognition signal on lysosomal acid hydrolases file:DANRE/gnptab/gnptab-deep-research-falcon.md GNPT functions in the **cis-Golgi**; GNPTAB is membrane-anchored with luminal active sites oriented toward the Golgi lumen, supported by structural topology and colocalization with **GM130**. |
| GO:0003976 UDP-N-acetylglucosamine-lysosomal-enzyme N-acetylglucosaminephosphotransferase activity | ISS GO_REF:0000024 | ACCEPT | Summary: UDP-N-acetylglucosamine-lysosomal-enzyme N-acetylglucosaminephosphotransferase activity (GO:0003976) is supported for gnptab. This ISS annotation is directly confirmed by the zebrafish-specific structural study (UniProt Q5RGJ8) reported in the falcon deep research. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: file:DANRE/gnptab/gnptab-uniprot.txt Catalyzes the formation of mannose 6-phosphate recognition markers on lysosomal enzymes PMID:23733939 mediates the initial step in the formation of the mannose 6-phosphate recognition signal on lysosomal acid hydrolases file:DANRE/gnptab/gnptab-deep-research-falcon.md A zebrafish GNPTAB catalytic construct (UniProt Q5RGJ8) was structurally solved with bound **UDP-GlcNAc**, mapping mechanistic features including: - A proposed general base **His956** to deprotonate the mannose O6, |
| GO:0003007 heart morphogenesis | IMP PMID:33055423 Inappropriate cathepsin K secretion promotes its enzymatic a... | KEEP AS NON CORE | Summary: heart morphogenesis (GO:0003007) is retained as supported context for gnptab but is not the primary/core function. It is a downstream developmental consequence of impaired lysosomal targeting; falcon deep research notes gnptab-deficient zebrafish show cardiac edema among broad developmental phenotypes, and inappropriately secreted/activated cathepsins drive the pathology. Reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the central molecular role. Supporting Evidence: PMID:33055423 Without Gnptab, lysosomal hydrolases, including cathepsin proteases, are inappropriately secreted file:DANRE/gnptab/gnptab-deep-research-falcon.md Zebrafish gnptab depletion (morpholino-based MLII models) causes reduced mannose phosphorylation of lysosomal hydrolases and broad developmental phenotypes (craniofacial cartilage, cardiac edema, otic vesicle/otolith defects, pectoral fin defects, motility defects), with **rescue by wild-type GNPTAB mRNA**. |
| GO:0051216 cartilage development | IMP PMID:26404503 Cathepsin-Mediated Alterations in TGFΓ-Related Signaling Und... | KEEP AS NON CORE | Summary: cartilage development (GO:0051216) is retained as supported context for gnptab but is not the primary/core function. It is a downstream consequence of impaired lysosomal enzyme targeting: falcon deep research describes chondrocyte differentiation and ECM-homeostasis abnormalities in zebrafish gnptab MLII models, with chondrocytes failing to intercalate and being ~25% larger. Reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the central molecular role. Supporting Evidence: PMID:26404503 Hypersecretion of acid hydrolases is a hallmark feature of mucolipidosis II (MLII) file:DANRE/gnptab/gnptab-deep-research-falcon.md Chondrocytes fail to intercalate and are reported **~25% larger** than wild-type. |
| GO:0051216 cartilage development | IGI PMID:26404503 Cathepsin-Mediated Alterations in TGFΓ-Related Signaling Und... | KEEP AS NON CORE | Summary: cartilage development (GO:0051216) is retained as supported context for gnptab but is not the primary/core function. The genetic-interaction evidence reflects the downstream protease-driven mechanism: falcon deep research reports that in gnptab-deficient embryos there is increased and sustained cathepsin and MMP activity (regionally enriched in the head), linking lysosomal mistargeting to extracellular protease-driven cartilage pathology. Reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the central molecular role. Supporting Evidence: PMID:26404503 Hypersecretion of acid hydrolases is a hallmark feature of mucolipidosis II (MLII) file:DANRE/gnptab/gnptab-deep-research-falcon.md In gnptab-deficient embryos, there is increased and sustained activity of cathepsins and MMPs, regionally enriched in the head, linking lysosomal mistargeting to extracellular protease-driven cartilage pathology. |
| GO:0060348 bone development | IMP PMID:26404503 Cathepsin-Mediated Alterations in TGFΓ-Related Signaling Und... | KEEP AS NON CORE | Summary: bone development (GO:0060348) is retained as supported context for gnptab but is not the primary/core function. Skeletal phenotypes are downstream of impaired M6P-dependent lysosomal targeting; falcon deep research frames loss of mannose phosphorylation as causing secretion of lysosomal hydrolases and secondary tissue pathology rather than a direct role in bone formation. Reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the central molecular role. Supporting Evidence: PMID:26404503 Hypersecretion of acid hydrolases is a hallmark feature of mucolipidosis II (MLII) file:DANRE/gnptab/gnptab-deep-research-falcon.md loss of GNPT activity abolishes M6P labeling and causes missorting/secretion of lysosomal enzymes, with secondary lysosomal dysfunction and storage. |
| GO:0060348 bone development | IGI PMID:26404503 Cathepsin-Mediated Alterations in TGFΓ-Related Signaling Und... | KEEP AS NON CORE | Summary: bone development (GO:0060348) is retained as supported context for gnptab but is not the primary/core function. The genetic-interaction evidence reflects the downstream cathepsin/MMP protease mechanism described in falcon deep research, in which sustained protease activity following lysosomal mistargeting disrupts skeletal maturation. Reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the central molecular role. Supporting Evidence: PMID:26404503 Hypersecretion of acid hydrolases is a hallmark feature of mucolipidosis II (MLII) file:DANRE/gnptab/gnptab-deep-research-falcon.md In gnptab-deficient embryos, there is increased and sustained activity of cathepsins and MMPs, regionally enriched in the head, linking lysosomal mistargeting to extracellular protease-driven cartilage pathology. |
| GO:0051216 cartilage development | IMP PMID:25505245 Analysis of mucolipidosis II/III GNPTAB missense mutations i... | KEEP AS NON CORE | Summary: cartilage development (GO:0051216) is retained as supported context for gnptab but is not the primary/core function. It is a downstream developmental consequence of reduced M6P tagging; falcon deep research reports altered chondrocyte differentiation and ECM markers (reduced aggrecan, sustained col2a1/type II collagen) in zebrafish gnptab MLII models. Reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the central molecular role. Supporting Evidence: PMID:25505245 GlcNAc-1-phosphotransferase tags newly synthesized lysosomal enzymes with mannose 6-phosphate recognition markers file:DANRE/gnptab/gnptab-deep-research-falcon.md Transcriptional/ECM markers: reduced aggrecan and sustained/high col2a1/type II collagen transcripts at later stages were reported. |
| GO:0003976 UDP-N-acetylglucosamine-lysosomal-enzyme N-acetylglucosaminephosphotransferase activity | IMP PMID:25505245 Analysis of mucolipidosis II/III GNPTAB missense mutations i... | ACCEPT | Summary: UDP-N-acetylglucosamine-lysosomal-enzyme N-acetylglucosaminephosphotransferase activity (GO:0003976) is supported for gnptab. Falcon deep research confirms the active-site architecture and catalytic determinants of this activity in the zebrafish enzyme, including residues whose mutation drastically reduces phosphotransferase activity. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: PMID:25505245 GlcNAc-1-phosphotransferase tags newly synthesized lysosomal enzymes with mannose 6-phosphate recognition markers file:DANRE/gnptab/gnptab-deep-research-falcon.md Quantitatively, mutation of **Asp407** reduced activity by ~**500-fold**, and mutation of **Asn1151** reduced activity by ~**200-fold** in the reported assays. |
| GO:0016256 N-glycan processing to lysosome | IMP PMID:25505245 Analysis of mucolipidosis II/III GNPTAB missense mutations i... | ACCEPT | Summary: N-glycan processing to lysosome (GO:0016256) is supported for gnptab. Falcon deep research describes the substrate-recognition determinants required for selective phosphorylation of lysosomal hydrolase N-glycans, including the DMAP interaction domain that binds cathepsin D and alpha-iduronidase but not tested non-lysosomal glycoproteins. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: PMID:25505245 GlcNAc-1-phosphotransferase tags newly synthesized lysosomal enzymes with mannose 6-phosphate recognition markers file:DANRE/gnptab/gnptab-deep-research-falcon.md A **DMAP interaction domain** within GNPTAB serves as a **substrate-recognition module**, experimentally binding lysosomal hydrolases (cathepsin D, Ξ±-iduronidase) but not tested non-lysosomal glycoproteins. |
| GO:0016256 N-glycan processing to lysosome | ISS GO_REF:0000024 | ACCEPT | Summary: N-glycan processing to lysosome (GO:0016256) is supported for gnptab. Falcon deep research describes the two-step M6P tagging pathway initiated by GNPTAB and completed by the uncovering enzyme to expose M6P for receptor-mediated sorting of lysosomal hydrolases. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: file:DANRE/gnptab/gnptab-uniprot.txt Catalyzes the formation of mannose 6-phosphate recognition markers on lysosomal enzymes PMID:23733939 mediates the initial step in the formation of the mannose 6-phosphate recognition signal on lysosomal acid hydrolases file:DANRE/gnptab/gnptab-deep-research-falcon.md GNPTAB initiates formation of the M6P sorting signal that enables downstream receptor-based routing of lysosomal enzymes; loss of GNPT activity abolishes M6P labeling and causes missorting/secretion of lysosomal enzymes, with secondary lysosomal dysfunction and storage. |
| GO:0005794 Golgi apparatus | ISS GO_REF:0000024 | ACCEPT | Summary: Golgi apparatus (GO:0005794) is supported for gnptab. Falcon deep research localizes GNPTAB function to the cis-Golgi, consistent with structural topology and GM130 colocalization, and notes that S1P-mediated activation and Golgi retention occur in the Golgi/TGN. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: file:DANRE/gnptab/gnptab-uniprot.txt Catalyzes the formation of mannose 6-phosphate recognition markers on lysosomal enzymes PMID:23733939 mediates the initial step in the formation of the mannose 6-phosphate recognition signal on lysosomal acid hydrolases file:DANRE/gnptab/gnptab-deep-research-falcon.md GNPTAB functions in the **cis-Golgi**, with its catalytic surfaces oriented toward the **Golgi lumen**, consistent with both structural topology and colocalization evidence (GM130 marker). |
| GO:0007040 lysosome organization | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: lysosome organization (GO:0007040) is retained as supported context for gnptab but is not the primary/core function. It is an indirect consequence: by tagging hydrolases for delivery, GNPTAB supports lysosomal function, and falcon deep research notes that loss of GNPT causes secondary lysosomal dysfunction and storage rather than direct lysosome biogenesis. Reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the central molecular role. Supporting Evidence: file:DANRE/gnptab/gnptab-uniprot.txt Catalyzes the formation of mannose 6-phosphate recognition markers on lysosomal enzymes PMID:23733939 mediates the initial step in the formation of the mannose 6-phosphate recognition signal on lysosomal acid hydrolases file:DANRE/gnptab/gnptab-deep-research-falcon.md loss of GNPT activity abolishes M6P labeling and causes missorting/secretion of lysosomal enzymes, with secondary lysosomal dysfunction and storage. |
| GO:0046835 carbohydrate phosphorylation | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: carbohydrate phosphorylation (GO:0046835) is retained as supported context for gnptab but is not the primary/core function. It is a broad parent describing the chemistry; falcon deep research specifies that GNPTAB phosphorylates the 6-hydroxyl of mannose on N-glycans, which is more precisely captured by the phosphotransferase activity (GO:0003976) core annotation. Reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the central molecular role. Supporting Evidence: file:DANRE/gnptab/gnptab-uniprot.txt Catalyzes the formation of mannose 6-phosphate recognition markers on lysosomal enzymes PMID:23733939 mediates the initial step in the formation of the mannose 6-phosphate recognition signal on lysosomal acid hydrolases file:DANRE/gnptab/gnptab-deep-research-falcon.md Zebrafish GNPTAB catalyzes the first step of M6P tag formation by transferring **phospho-GlcNAc** from **UDP-GlcNAc** to the **6-hydroxyl of mannose** on N-glycans (including high-mannose glycans of lysosomal hydrolases). |
| GO:0003976 UDP-N-acetylglucosamine-lysosomal-enzyme N-acetylglucosaminephosphotransferase activity | IMP PMID:23733939 The DMAP interaction domain of UDP-GlcNAc:lysosomal enzyme N... | ACCEPT | Summary: UDP-N-acetylglucosamine-lysosomal-enzyme N-acetylglucosaminephosphotransferase activity (GO:0003976) is supported for gnptab. This is the core molecular function; falcon deep research reports that in zebrafish, depletion reduces phosphotransferase activity (up to 89% inhibition by morpholino at 4 dpf) and the MLII-like phenotype is rescued by wild-type GNPTAB mRNA. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: PMID:23733939 mediates the initial step in the formation of the mannose 6-phosphate recognition signal on lysosomal acid hydrolases file:DANRE/gnptab/gnptab-deep-research-falcon.md Wild-type phosphotransferase activity was reported as **35β51 pmol/mg/h** during the first 5 days; morpholino knockdown achieved up to **89% inhibition** (4 dpf). |
| GO:0048703 embryonic viscerocranium morphogenesis | IMP PMID:23733939 The DMAP interaction domain of UDP-GlcNAc:lysosomal enzyme N... | KEEP AS NON CORE | Summary: embryonic viscerocranium morphogenesis (GO:0048703) is retained as supported context for gnptab but is not the primary/core function. Craniofacial cartilage defects are downstream of impaired M6P-dependent lysosomal targeting; falcon deep research lists craniofacial cartilage among the broad developmental phenotypes of zebrafish gnptab depletion, rescuable by wild-type mRNA. Reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the central molecular role. Supporting Evidence: PMID:23733939 mediates the initial step in the formation of the mannose 6-phosphate recognition signal on lysosomal acid hydrolases file:DANRE/gnptab/gnptab-deep-research-falcon.md Zebrafish gnptab depletion (morpholino-based MLII models) causes reduced mannose phosphorylation of lysosomal hydrolases and broad developmental phenotypes (craniofacial cartilage, cardiac edema, otic vesicle/otolith defects, pectoral fin defects, motility defects), with **rescue by wild-type GNPTAB mRNA**. |
| GO:0002063 chondrocyte development | IMP PMID:19834066 Altered chondrocyte differentiation and extracellular matrix... | KEEP AS NON CORE | Summary: chondrocyte development (GO:0002063) is retained as supported context for gnptab but is not the primary/core function. It is a downstream developmental consequence: falcon deep research describes altered chondrocyte differentiation in zebrafish gnptab MLII models, with chondrocytes failing to intercalate and being ~25% larger than wild-type. Reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the central molecular role. Supporting Evidence: PMID:19834066 N-acetylglucosamine-1-phosphotransferase, the enzyme that initiates mannose 6-phosphate biosynthesis file:DANRE/gnptab/gnptab-deep-research-falcon.md Chondrocytes fail to intercalate and are reported **~25% larger** than wild-type. |
| GO:0048701 embryonic cranial skeleton morphogenesis | IMP PMID:19834066 Altered chondrocyte differentiation and extracellular matrix... | KEEP AS NON CORE | Summary: embryonic cranial skeleton morphogenesis (GO:0048701) is retained as supported context for gnptab but is not the primary/core function. Craniofacial skeletal defects are a downstream consequence of impaired lysosomal targeting; falcon deep research links these to dysregulated cathepsin/MMP activity following reduced mannose phosphorylation, with rescue by wild-type mRNA. Reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the central molecular role. Supporting Evidence: PMID:19834066 N-acetylglucosamine-1-phosphotransferase, the enzyme that initiates mannose 6-phosphate biosynthesis file:DANRE/gnptab/gnptab-deep-research-falcon.md gnptab loss in zebrafish alters chondrocyte differentiation and ECM homeostasis: chondrocytes fail to intercalate, are **25% larger**, show high/ectopic **Sox9**, reduced **aggrecan**, sustained **col2a1/type II collagen**, and elevated cathepsin/MMP activity; WT GNPTAB mRNA normalizes cathepsin activity. |
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